Conventional sets of golf clubs include three types clubs called "woods," "irons," and putters. Each club is made up of a shaft having a club head attached to one end and a grip attached to the other end. The club head includes a face for striking a ball. The angle between the face and the shaft is called "loft." Each type of club has a distinguishable shaft length and club head loft.
The shaft length and the club head loft help determine the playing characteristics of the club. As the shaft length increases, the club head speed upon impact with the ball increases, and the ball travels farther. As the shaft length decreases, the club head speed upon impact with the ball decreases, and the ball travels a shorter distance. In addition, as the loft increases, the potential arc or trajectory of the ball in flight also increases. As the ball trajectory increases, the more the potential ball distance decreases. Conversely, as the loft decreases, the potential arc or trajectory of the ball in flight also decreases. As the ball trajectory decreases, the more the potential ball distance increases.
In an ideal swing the golfer aligns the club head with the golf ball, so that the club head impacts the ball straight. This allows the ball to move in the desired direction. A fast-swinging player is typically a tour or experienced male player. These players swing an iron at speeds of about 100 mph, and between 80 to 90 mph, respectively. Therefore, these players have the ability to generate enough speed for long distances. However, these players can experience problems with shaft tip stability. Tip stability is defined by the torsional rigidity and bending stiffness at the tip relative to the upper portion of the shaft.
Most shafts today are wider at the grip and taper down to a narrow tip end near the club head. When a fast-swinging player swings a club, torque forces tend to twist the tip of the shaft causing the club head to strike the ball at an angle. Furthermore, when the club head strikes the ball, a force is exerted on the club head by the ball, which tends to bend the shaft tip and un-square the club head. This twisting and bending of the tip leads to inaccurate shots.
In an effort to provide more tip stability, a number of solutions have been attempted. Some conventional golf club shafts have substituted various stronger composite materials in the shaft tip end in order to build up the sidewalls of the tip end. These composite materials, however, may be difficult to work with and expensive. In addition, these composite materials may have only limited benefits. Because the tip end has a small diameter, only a small amount of composite material may be added to the tip end, which may not significantly improve tip stability.
Other conventional shafts may attempt to improve the playing characteristics of a golf club and the tip stability by increasing the overall diameter of the entire shaft or by employing shafts with varying diameters or tapers. An oversized diameter shaft may have a stiffer, more stable tip end, but it may also have an oversized grip section that may be too large for most players. In addition, the oversized diameter shaft may be too heavy or too stiff, so that it does not feel good to most golfers. Other conventional shafts may have non-constant tapers that improve the playing characteristics of the golf club, but these non-constant tapered shafts are more difficult to manufacture and more costly. These non-constant taper shafts may also be too heavy. It is desirable to improve shaft tip stability for fast-swinging players, while maintaining the feel of a conventional club.
Slow-swinging players have a need for tip stability, due to for example, maintaining accuracy after the club head impacts the ground. The stiff shaft that fast-swinging players use may not improve the games of slow-swinging players. However, tip stability is still a consideration. Slow-swinging players are usually seniors, women, or inexperienced players. These players swing irons at speeds of for example 70 mph for seniors and 65 mph for women. Therefore, they have difficulty generating enough speed for long distances. These players also have difficulty getting a higher trajectory with the ball.
To combat their distance problem, these players typically use more flexible shafts, which create a whip-action. The whip-action compensates for the physical or skill deficits of these players, and accelerates the club head, which causes the head to drive the ball longer. Although ball rise is important, the need for whip-action must be balanced against the player's need for tip stability.
Since slow-swinging players have difficulty getting the higher ball trajectory, they tend to drive the ball into the ground, which limits the ball distance. Long irons do not alleviate this problem, because of their low loft. In an effort to increase their distance, these players may resort to using middle and short irons for their "distance" shots. The middle and short irons, which have greater loft, will help increase the vertical flight of their shots. However, players that use these clubs for "distance" shots sacrifice the potential distance benefits of the long irons for the loft of the other irons.
As golf has gained popularity, there is a need for clubs, which improve the games of players with varying skills. In order to minimize the cost of providing clubs for fast-swinging and slow-swinging players, it is desired that clubs be devised that may be used to improve tip stability for fast-swinging players, and distance and ball trajectory for slow-swinging players.